Nerve cells, or "neurons," consist of a cell body (the "soma") and an "axon" projecting from the cell body through which nerve impulses travel. Injuries to neurons involving transection of, or damage to, the axons (termed "axotomy") characteristically result in retrograde neuronal dysfunction or death to most of these cells. Such injuries may result, for example, from trauma to the head or spinal cord, or as an unavoidable consequence of surgical procedures intended to correct certain conditions of the nervous system. In addition, damage to axons may occur as a result of neurodegenerative disease.